This invention relates generally to railroad rails and more particularly to methods and apparatus for inducing ultrasonic waves into railroad rails.
Some known rail inspection techniques include eddy current analysis wherein perturbations in an electric current induced into the rail is indicative of defects, and electromagnetic analysis, wherein perturbations in magnetic flux induced into the rail are examined to reveal anomalies. Eddy current analysis and electromagnetic analysis have range limitations that make their use more time consuming and more expensive than using ultrasonic analysis. To facilitate inspection, other known inspection techniques include ultrasonic analysis wherein reflections of sound waves induced into the rail are evaluated to locate and characterize defects. Some known ultrasonic techniques use a piezoelectric principle to induce ultrasonic waves into railroad rails. A piezoelectric transducer is held in close contact with the rail while activated to induce ultrasonic waves into the rail. The piezoelectric technique has disadvantages that limits its usefulness as a cost-effective and reliable inspection tool. For example, the piezoelectric transducer generates transverse waves which have a limited range in the rail.
In one aspect, a method of inducing ultrasonic waves into a railroad rail is described. The method includes locating at least one magnetic exciter adjacent to the rail, the at least one magnetic exciter includes an emitting end and a longitudinal axis extending perpendicularly through the emitting end, discharging the energy storage circuit through the at least one magnetic exciter such that only a magnetic pulse enters the rail at a location of the exciter, and controlling a shape of the magnetic pulse.
In another aspect of the present invention, an apparatus for inducing ultrasonic waves into a railroad rail is described. The apparatus includes at least one magnetic exciter adjacent to the rail, an energy storage circuit electrically coupled to the at least one magnetic exciter, the energy storage circuit configured to supply a shaped current pulse to the at least one exciter, and a power source electrically coupled to the energy storage circuit configured to charge the energy storage circuit with electrical energy.
In a further aspect, a railroad locomotive is described. The locomotive includes a platform having a first end and a second end, a propulsion system coupled to the platform for supporting and propelling the platform on a pair of rails, and a rail ultrasonic wave inducement system comprising at least one magnetic exciter, a energy storage circuit electrically coupled to the at least one magnetic exciter, and a power source electrically coupled to the energy storage circuit, the at least one magnetic exciter is coupled to the locomotive such that the at least one magnetic exciter moves in concert with the locomotive and maintains a position adjacent to a rail, the energy storage circuit is configured to supply at least one of sequential current pulses to the at least one magnetic exciter and simultaneous current pulses to the at least one magnetic exciter according to a predetermined configuration, the energy storage circuit is further configured to control a shape of the pulses.
In yet another aspect, a railroad vehicle is described. The vehicle includes a platform having a first end and a second end, a truck coupled to the platform for supporting the platform on a pair of rails, and a rail ultrasonic wave inducement system comprising at least one magnetic exciter, a energy storage circuit electrically coupled to the at least one magnetic exciter, and a power source electrically coupled to the energy storage circuit, the at least one magnetic exciter is coupled to the vehicle such that the at least one magnetic exciter moves in concert with the vehicle and maintains a position adjacent to a rail, the energy storage circuit is configured to supply at least one of sequential current pulses to the at least one magnetic exciter and simultaneous current pulses to the at least one magnetic exciter according to a predetermined configuration, the energy storage circuit is further configured to control a shape of the pulses.